Modeling Nonfunctional Requirements

In one perspective, all of these items can be considered to be constraints on new development, in that each eliminates some degree of design freedom on the part of those building the system. Here’s an example:

“For compatibility with our partners, we have agreed to implement SAML-based Single Sign On (SSO is a functional requirement, basing it on SAML is a constraint) for all products in the suite.”

“Every product in the suite has to be internationalized (constraint), but only the Order Entry module must be localized to Korean (functional requirement) for this release.”